Wilhelm, K. MPI for Aeronomy, Max Planck Institute for Solar System Research, Max Planck Society; Department Sun and Heliosphere, Max Planck Institute for Solar System Research, Max Planck Society;
Lemaire, P., Bocchialini, K., Aletti, V., Hassler, D., & Wilhelm, K. (1999). Search for Signatures of a Coronal Hole in Transition Region Lines Near Disk Center. Space Science Reviews, 87, 249-252.